fixup! Refactoring: Relocate content from "explain" into "solution" again

Author: amotl

docs/explain/index.md

@@ -11,3 +11,12 @@ Broaden and deepen your knowledge and understanding of CrateDB subject matters.
 The explanatory guides in this section provide more context and background
 about applications and use cases of CrateDB, trying to put things into a
 bigger picture and joining things together to help answer the question _why_?
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+
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+:::{note}
+You can expect the more recent documents to be more up-to-date than previous
+ones. If you can discover any flaws, please report them back to us by
+navigating to the tool flyout in the top right corner of each page,
+then using "Suggest improvement" to leave your feedback.
+:::